Re: [PATCH 3/7 V2] workqueue: introduce get_pwq_unlocked()

[Tejun Heo <tj@kernel.org>]

Hello, Lai.

On Tue, May 12, 2015 at 08:32:31PM +0800, Lai Jiangshan wrote:
> attrs management code may reuse existed pwq and it has open code

                                  existing

> to do "lock();get_pwq();unlock()", we move this open code into
> get_pwq_unlocked().
> 
> get_pwq_unlocked() will also be used in later patches to allow
> apply_wqattrs_prepare() to resue the original default or per-node pwq.
> 
> Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
...
> +install:
>  	/* Install the new pwq. */
>  	mutex_lock(&wq->mutex);
>  	old_pwq = numa_pwq_tbl_install(wq, node, pwq);
> -	goto out_unlock;
> -
> -use_dfl_pwq:
> -	mutex_lock(&wq->mutex);
> -	spin_lock_irq(&wq->dfl_pwq->pool->lock);
> -	get_pwq(wq->dfl_pwq);
> -	spin_unlock_irq(&wq->dfl_pwq->pool->lock);
> -	old_pwq = numa_pwq_tbl_install(wq, node, wq->dfl_pwq);
> -out_unlock:
>  	mutex_unlock(&wq->mutex);
>  	put_pwq_unlocked(old_pwq);
>  }

This doens't strike me as better.  If we have other places where the
unlocked get is used, maybe, but that's not the case.

Thanks.

-- 
tejun